Results 1 to 6 of 6

Math Help - Limits...

  1. #1
    Banned
    Joined
    Aug 2007
    Posts
    52

    Limits...

    hey i have a question about a limit problem. i tried putting values less than 0 i.e. .1, .01, .001...and so on but it didnt seem to work...help?

    lim as x-->theta of theta/tan(4theta)

    thanks...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    9
    Quote Originally Posted by mer1988 View Post
    hey i have a question about a limit problem. i tried putting values less than 0 i.e. .1, .01, .001...and so on but it didnt seem to work...help?

    lim as x-->theta of theta/tan(4theta)

    thanks...
    Be sure you are in radians.

    \left\{ \begin{array}{cc} \theta & \frac{\theta}{\tan (4\theta)} \\ 1 & .8637 \\.1 &  .2365 \\ .01 & .2499 \\ .001& .2500 \end{array} \right.

    So what do you think it is?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Banned
    Joined
    Aug 2007
    Posts
    52
    Quote Originally Posted by ThePerfectHacker View Post
    Be sure you are in radians.

    \left\{ \begin{array}{cc} \theta & \frac{\theta}{\tan (4\theta)} \\ 1 & .8637 \\.1 & .2365 \\ .01 & .2499 \\ .001& .2500 \end{array} \right.

    So what do you think it is?

    those are the outcomes for the values less than zero and the other thing is like a limit def. or something
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,939
    Thanks
    338
    Awards
    1
    Quote Originally Posted by mer1988 View Post
    hey i have a question about a limit problem. i tried putting values less than 0 i.e. .1, .01, .001...and so on but it didnt seem to work...help?

    lim as x-->theta of theta/tan(4theta)

    thanks...
    Try this:
    \lim_{\theta \to 0}\frac{\theta}{tan(4\theta)}

    Change the variable to \alpha = 4 \theta. Then \alpha \to 0 as \theta \to 0. Thus

    \lim_{\theta \to 0}\frac{\theta}{tan(4\theta)} = \lim_{\alpha \to 0}\frac{\frac{1}{4} \alpha}{tan(\alpha)} = \frac{1}{4} \cdot <br />
\lim_{\alpha \to 0}\frac{\alpha}{tan(\alpha)}

    Does this help?

    -Dan
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Math Engineering Student
    Krizalid's Avatar
    Joined
    Mar 2007
    From
    Santiago, Chile
    Posts
    3,654
    Thanks
    13
    Quote Originally Posted by topsquark View Post
    Try this:
    \lim_{\theta \to 0}\frac{\theta}{tan(4\theta)}

    Change the variable to \alpha = 4 \theta. Then \alpha \to 0 as \theta \to 0. Thus

    \lim_{\theta \to 0}\frac{\theta}{tan(4\theta)} = \lim_{\alpha \to 0}\frac{\frac{1}{4} \alpha}{tan(\alpha)} = \frac{1}{4} \cdot <br />
\lim_{\alpha \to 0}\frac{\alpha}{tan(\alpha)}

    Does this help?
    Is not necessary to set a change of variable

    \lim_{\theta\to0}\frac\theta{\tan4\theta}=\frac14\  lim_{\theta\to0}\frac{4\theta}{\tan4\theta}

    Then it's done...
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,939
    Thanks
    338
    Awards
    1
    Quote Originally Posted by Krizalid View Post
    Is not necessary to set a change of variable

    \lim_{\theta\to0}\frac\theta{\tan4\theta}=\frac14\  lim_{\theta\to0}\frac{4\theta}{\tan4\theta}

    Then it's done...
    (snort!) I always do things the hard way...

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Using limits to find other limits
    Posted in the Calculus Forum
    Replies: 7
    Last Post: September 18th 2009, 05:34 PM
  2. Function limits and sequence limits
    Posted in the Differential Geometry Forum
    Replies: 0
    Last Post: April 26th 2009, 01:45 PM
  3. HELP on LIMITS
    Posted in the Calculus Forum
    Replies: 4
    Last Post: September 23rd 2008, 11:17 PM
  4. Limits
    Posted in the Calculus Forum
    Replies: 5
    Last Post: September 21st 2008, 10:52 PM
  5. [SOLVED] [SOLVED] Limits. LIMITS!
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 25th 2008, 10:41 PM

Search Tags


/mathhelpforum @mathhelpforum